Cognitive impairment of Chinese patients with multiple sclerosis and neuromyelitis optica

Abstract

INTRODUCTION: Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are important central nervous system inflammatory demyelinating disorders. Cognitive impairment is increasingly recognized in both MS and NMOSD. METHODS: We studied cognitive functions of Chinese MS and NMOSD patients followed up in QMH by using a Chinese version of Rao’s Brief Repeatable Battery of Neuropsychological Tests (BRBN). The BRBN consists of five groups of tests: 1) Symbol Digit Modalities Test (SDMT) and 2) Paced Auditory Serial Addition Test (PASAT) for sustained attention, concentration and speed of information processing, 3) Selective Reminding Test (SRT) for verbal immediate and delayed recall memory, 4) 10/36 Spatial Recall Test (SPART) for spatial immediate and delayed recall memory, and 5) Word List Generation Test (WLG) for verbal fluency on semantic stimulus; yielding total 9 test scores. An abnormal score is defined as below the fifth percentile of the normative value derived from healthy subjects. Patients with abnormal scores in 3 or more tests were diagnosed as having cognitive impairment. RESULTS: 30 healthy subjects (16 men, mean age 37.3 years, range 21-56), 17 NMOSD patients (15 women, mean age 47 years, range 28-69) and 21 MS patients (14 women, mean age 40.5 years, range 18-59) were studied. The mean disease duration was 80.5 months, the mean latest EDSS score was 2.7, 13 (76.%%) were AQP4 antibody +ve and 10 (58.8%) had MRI brain abnormalities for the NMOSD patients. The mean disease duration was 141.7 months and the mean latest EDSS score was 3.5 for the MS patients. Among the 17 NMOSD patients, 5 (31.3%) had impaired SDMT, 6 (35.3%) had impaired SRT, 7 (41.2%) had impaired SPART, 7 (41.2%) had impaired PASAT and 7 (41.2%) had impaired WLG. Overall, 8 NMOSD patients (47.1%) had cognitive impairment. Among the 21 MS patients, 15 (71.4%) had impaired SDMT, 10 (47.6%) had impaired SRT, 9 (42.9%) had impaired SPART, 14 (66.7%) had impaired PASAT and 14 (66.7%) had impaired WLG). Overall, 15 MS patients (71.4%) had cognitive impairment. CONCLUSION: Cognitive impairment is common among NMOSD and MS patients.